Various software data items (hereinafter, referred to as contents) such as audio data such as music, image data such as video, a game program, and various application programs, can be stored in a recording medium, for example, a disk type information recording medium such as a Blu-ray (registered trademark) disc or a digital virsatile disc (DVD) or an information recording medium such as a flash memory.
A content storage medium, for example, is used for reproducing the content by being mounted on a reproducing device such as a personal computer (PC) or a player possessed by a user.
The reproducing device is capable of acquiring data (subsequent data) corresponding to a content recorded in an information recording medium which is mounted on the reproducing device, from a server. For example, in a case where the content recorded in the information recording medium is a video content, a content (subsequent data) such as various moving images and static images, for example, subtitle data or dubbed data corresponding to the video content, and service data corresponding to the content, preview, advertising, and the like, are acquired from the server.
The reproducing device such as a PC or a disk player, for example, stores the subsequent data acquired from the server in a hard disk which is embedded in the reproducing device.
When the reproducing device reproduces the content recorded in the information recording medium which is mounted on the reproducing device, it is possible to read out subsequent data corresponding to the mounted medium from the hard disk and to reproduce the subsequent data along with the content stored in the medium.
Furthermore, a content using system where the subsequent data is acquired from the server or the like, is recorded in a local storage unit of a user device, such as a hard disk, and is reproduced along with the content recorded in the disk, for example, is disclosed in Patent Document 1 (Japanese Patent No. 3959735) or Patent Document (Japanese Patent Application Laid-Open No. 2003-140662).
For example, when the content recorded in the disk such as a Blu-ray (registered trademark) disc, and the subsequent data recorded in the local storage unit such as the hard disk are reproduced together in the user device, a package virtual package is set in which the content stored in the disk and the content stored in the local storage unit such as the hard disk are integrated, a virtual file system (VFS) is constructed, and reproduction processing is performed. According to the reproduction processing based on the VFS, it is possible to perform reproduction similar to reproduction processing performed as if from one medium.
The number of subsequent data items is not limited to one with respect to one disk. That is, various subsequent data items are sequentially provided from the server. For example, various subsequent data items such as preview information with respect to a video content stored on one disk, advertising information of a company A, and advertising information of a company B are sequentially provided from the server.
In addition, various disks are mounted on the user device, and the subsequent data corresponding to each of the mounted disks is acquired from the server, and is stored in the local storage unit of the user device, such as the hard disk.
A subsequent data recording area of each of the disks, corresponding to each of the disks, is set in the local storage unit, and the subsequent data corresponding to each of the disks is recorded in the subsequent data recording area of each of the disks.
That is, a directory in the disk unit is set in the local storage unit of the user device, and the subsequent data corresponding to each of the disks is recorded within the directory in the disk unit.
In a case where the disk is mounted, the user device constructs the virtual file system (VFS) for selectively acquiring data within the directory where the subsequent data corresponding to the disk is recorded, and performs reproduction processing.
In order to perform such processing, the user device is required to specify the directory where the subsequent data corresponding to the disk mounted on the user device is stored.
For example, a directory name of the directory in which the subsequent data corresponding to the disk is recorded is acquired, the directory having the acquired directory name is extracted, and virtual file system (VFS) construction processing is executed.
Patent Document 3 (Japanese Patent No. 4806396) is provided as the related art disclosing such processing of acquiring the directory corresponding to the disk.
In Patent Document 3, a configuration is disclosed in which a hash value is calculated from a disk root certificate which is recorded in the disk mounted on the user device, that is, a root certificate which is a public key certificate corresponding to a content producer, a directory name corresponding to the calculated hash value is retrieved from the local storage unit, data within the directory is determined as the subsequent data recording area corresponding to the mounted disk, and the virtual file system (VFS) is constructed.
However, recently, for example, the use of an ultra high definition (UHD) image content such as a 4K content or an 8K content has increased, in addition to the use of a currently prevailing high definition (HD) image content.
Hereafter, it is expected that a situation in which the HD image content and the UHD image content are used together continues for a while.
The HD content and the UHD content, for example are different in an encoding (codec) aspect or the like, and a reproducing device corresponding to UHD and a display corresponding to UHD are required in order to reproduce and display a UHD image.
A lot of currently prevailing user devices such as a reproducing device or a display correspond to the HD content, but a user device (a reproducing device/a display) corresponding to UHD is still uncommon.
Accordingly, it is expected that a content making company, for example, makes both of the HD content and the UHD content with respect to the same video content, and supplies both of a disk storing the HD content and a disk storing the UHD content to the user.
In this case, even in the subsequent data described above, it is necessary that subsequent data corresponding to HD and subsequent data corresponding to UHD are made, and the reproducing device of the user acquires the subsequent data corresponding to HD or the subsequent data corresponding to UHD according to a user usage content from the server, and stores the subsequent data in the local storage unit of the user device.
However, in this case, in a case where the configuration of Patent Document 3 described above is applied, the following problems occur at the time of performing processing of acquiring the subsequent data corresponding to the mounted disk.
That is, a content producer of the subsequent data corresponding to the HD content is identical to a content producer of the subsequent data corresponding to UHD, and a disk root certificate which is stored in the disk storing the HD image content (a disk of a version 1) is identical to a disk root certificate which is stored in the disk storing the UHD image content (a disk of a version 2).
In this case, even in a case where the disk mounted on the reproducing device of the user is the disk storing the HD content (the disk of the version 1) or the disk storing the UHD content (the disk of the version 2), hash values which are calculated on the basis of the disk root certificate read out from the disks, are the same hash value.
Accordingly, in a case where the hash value calculated on the basis of the disk root certificate is set to the directory name of the directory of the local storage unit, in which the subsequent data is stored, a subsequent data storage area corresponding to an HD image is not capable of being distinguished from a subsequent data storage area corresponding to a UHD image.
As a result thereof, when the UHD image content is reproduced from the disk storing the UHD content (the disk of the version 2), there is a possibility that the reproducing device erroneously selects the HD image content from the local storage unit, as the subsequent data corresponding to the disk, and reproduces the HD image content.
In addition, in the case of a reproducing device which is not capable of reproducing the UHD image, or a reproducing device to which a display which is not capable of displaying the UHD image is connected, when the HD image content is reproduced from the disk storing the HD content (the disk of the version 1), there is also a possibility that the UHD image content is erroneously read out from the local storage unit, as the subsequent data corresponding to the disk, and thus, is not capable of being reproduced or displayed.